Engine assemblies may include a cam phaser that is coupled to an engine camshaft to adjust timing of intake and/or exhaust valve opening events. Adjusting valve timing based on engine operating conditions may provide increased engine performance, such as increased power output, reduced fuel consumption, and/or reduced engine emissions. Increasing the extent that the camshaft may be advanced or retarded may provide for increased performance gains.
Typical vane cam phasing devices (“cam phasers”) include a rotor and a stator, and have a positive stop position at the default or home position by using interference between the stator and the rotor to stop the rotational movement of the rotor at engine shut down. This allows a locking pin device to engage freely into its seat at engine shut-down to lock the rotor with respect to the stator. The cam phaser is prepared for engine start-up in this locked position. A mid-park cam phaser must lock at an intermediate position where this natural positive stop is not present, i.e., the rotor does not rest against the stator, and thus the lock pin may have difficulty engaging into its seat.